Port number after frimware upgrade?

Okay. Just got a GSM Cingular T600 with new number... currently also have ATT Nokia 6200 phone.

ATT ends May 20th... want to port my number to the t600 after that date. (They gave me some 551 area code crazy number on the cingular)

I've been told by the reseller, A1 Wireless, this won't be an issue.
Just curious, that now that I've done the firmware upgrade, is it going to be a problem? My HS SN number no longer matches the one on the back of the phone.
I'm not sure how the whole porting thing works...